Electromagnetic relay



July 18, 1961 J. s. ZIMMER ELECTROMAGNETIC RELAY 2 Sheets-Sheet FiledJan. 21, 1959 Oh azimmh :00

INVENTOR R Y E E M M M l 0 Z T s M N H S O H J July 18, 1961 J. s.ZIMMER 2,993,104

ELECTROMAGNETIC RELAY Filed Jan. 21, 1959 2 Sheets-Sheet 2 FlG.4

TE MINAL No.2

INVENTORI JOHN S. ZIMMER,

BY m /lw/ K d HI ATTORNEY.

United States Patent 2,993,104 ELECTROMAGNETIC RELAY John S. Zimmer,Waynesboro, Va., assignor to General Electric Company, a corporation ofNew York Filed Jan. 21, 1959, Ser. No. 788,197 11 Claims. (Cl. 200-103)The invention relates to an electromagnetic relay and its manufacture,and particularly to an electromagnetic single-pole double-throw relaythat may have relatively small dimensions, and that can be manufacturedin large quantities with mass-production methods.

An object of the invention is to provide an improved electromagneticsingle-pole double-throw relay that may have relatively small physicaldimensions.

Another object of the invention is to provide an improvedelectromagnetic single-pole double-throw relay that can be manufacturedwith mass-production methods.

Another object of the invention is to provide an improved method ofmanufacturing an electromagnetic relay.

These and other objects are accomplished in accordance with theinvention by an electromagnetic relay which, briefly, comprises a corehaving first and second elements of magnetic material, the two elementsbeing separated by a gap. An elongated spring has one end fastened tothe first core element and the other end positioned in the vicinity ofbut normally separated from the second core element. In one embodimentof the invention, an armature of magnetic material is fastened to thespring so that the armature is positioned in the vicinity of the gap butnormally separated from the two core elements. In another embodiment ofthe invention, the spring itself is formed from a magnetic material andserves as the armature. A stationary contact is positioned adjacentthe'spring and the spring is biased so that the spring normally engagesthe contact. And finally, an energizing coil is positioned around thecore elements, the spring, the armature, and the contact. The spring andfirst core element form a common terminal for the relay, the contactforms the normally closed switch terminal for the relay, and the secondcore element forms the normally open switch terminal for the relay. Whenthe coil is de-energized, a closed electrical circuit is providedbetween the first core element and the contact. When the coil isenergized, a closed electrical circuit is then provided between thefirst core element and the second core element.

The invention will be better understood from the following descriptiontaken in connection with the accompanying drawing and its scope will bepointed out in the claims. In the drawing:

FIGURE 1 shows a longitudinal cross-sectional view of a preferredembodiment of an electromagnetic relay in accordance with the invention,the view being taken along the lines 1-1 of FIGURE 2;

FIGURE 2 shows a transverse cross-sectional view of the electromagneticrelay taken along the lines 22 of FIGURE 1;

FIGURE 3 shows an elevation view of the core elements and spring of theelectromagnetic relay of FIGURE 1 during a stage of manufacture of therelay;

FIGURE 4 shows a perspective view of an inner tube which supports thecontact bar and core elements of the relay;

FIGURE 5 shows a longitudinal cross-sectional view of another embodimentof an electromagnetic relay in accordance with the invention; and

FIGURE 6 shows a longitudinal cross-sectional view of another embodimentof an electromagnetic relay in accordance with the invention,

In the figures, the same reference numerals are used to refer to thesame elements. A longitudinal cross-sectional view of the completeelectromagnetic relay is shown in FIGURE 1, and a transversecross-sectional view is shown in FIGURE 2. The relay comprises a corehaving a first core element 12 and a second core element 14 both formedof a magnetic material such as soft iron. A material having low fluxretention is preferable in order to aid dropout of the relay when thecoil is de-energized. The first and second core elements 12, 14 areformed, in a manner which will be explained, from a blank 10 which isbest shown in FIGURE 3. Integral with the core elements 12, 14 arerespective back portions 16, 18 for supporting the relay structure andalso for providing a good path for the magnetic flux of the relay coil.The core elements 12, 14 are separated by an air gap 19 which, as seenin FIGURE 1, may be generally described as X-shaped, and which is formedby the free or inner end surfaces of the core elements 12, 14. Anarmature 20 is formed from the same blank 10 as the core elements 12, 14and has a shape which corresponds to or substantially fits in -a portionof the gap 19. The armature 20 is fastened to a spring 22 which in turnis fastened to the first core element 12 at the surface point 24 by anysuitable means such as welding. The spring 22 is preferably made of aflat elongated strip of resilient material such as beryllium copper, andis bent or shaped so that it rests substantially in the position shownin FIG- URE 1. The spring 22 carries a spring contact 26 preferablyformed of a high conductivity metal that is silver plated, the springcarried contact 26 being on the opposite side of the spring 22 from thearmature 20. The spring carried contact 26 normally (i.e., when therelay is released) engages a contact bar 30 which is also preferablyformed of a high conductivity metal that is silver plated. The contactbar 30 has an extension which is bent to provide a backstop 32 for thefree end 28 of the spring 22. The backstop 32 helps to reduce bouncingor oscillation of the spring 22 when the relay is released or droppedout to its normal position. The free end 28 of the spring 22 ispositioned in the vicinity of the second core element 14 but is normallyseparated therefrom. When the relay is energized and pulled up from itsnormal position, the free end 28 of the spring 22 engages a contact 34which is preferably formed of a high conductivity metal that is silverplated, and which is fastened to the second core element 14. Since thefree end 2 8 of the spring 22 provides an electrical circuit to thecontact 34 on the second core element 14, and since the free end 28 mayflex or whip when the relay is released or dropped out so that the freeend 28 engages the backstop 32 before the spring carried contact 26engages the contact bar 30, the entire spring 22 or at least the freeend 28 portion may preferably be plated or alloyed with a suitable highconductivity metal such as silver.

The contact bar 30 and its backstop 32 are supported by an inner tube40, which is shown most clearly inthe perspective view in FIGURE 4. Theinner tube 40 is formed from a suitable piece of cylindrical,non-magnetic material such as stainless steel so that it has endsupports 42, 44 which are joined by two strips 46. On the lower side andbetween the two strips 46, a semi-cylindrical support 48 is provided.This support- 48 carries the contact bar 30 and the backstop 32. Thecontact bar 30 is preferably fastened to the support 48 before the relayis assembled. The inner tube 40 is supported in an electricallyinsulated relation between the back portions 16, '18 of the respectivecore elements 12, 14 by electrically insulating cylindrical beads 50which surround the back portions 16, 18 and bear against the shouldersformed by the first and second core elements 12, 14 respectively. Thecylindrical beads 50 may be rigidly fastened to the back portions 16, 18by any suitable means. Glass beads are preferred as they can be fused tothe back portions 16, 18 to provide a hermetic seal. When in position,the inner tube 40 is outside the core elements 12, 14, the back portions16, 18 and the cylindrical beads 50. The inner tube 40 is supported byand rigidly fastened to the beads 50 by its respective end supports 42,44. A cylindrical metallic tube 60 of non-magnetic material surroundsthe inner tube 40 and the relay elements. The cylindrical tube 60 may befastened to the inner tube 40 around the entire circumference of theinner tube 40 at the end supports 42, 44 respectively under suchconditions as to hermetically seal the moving relay parts under the mostdesirable conditions, such as in an atmosphere of dry inert gas. Anoperating or energizing coil 62 is Wound around a suitable coil form 64,the coil form 64 being made of an electrically insulating material suchas a plastic. The ends 66 of the coil 62 are brought out at one end ofthe coil form 64 for connecting the coil 62 to external terminals. Theends of the inner tube 40 and the cylindrical tube 60 are insulated bybushings 68 which are formed from an electrically insulating materialsuch as a plastic and which are dimensioned so that they pass over therespective end portions 16, 18.

Suitable coil terminals 70 are provided and fastened to the ends 66 ofthe coils 62. Likewise, a switching terminal 72 is fastened to the backportion 16, a terminal 74 for the normally open contact 34 is fastenedto the back portion 18, and a terminal 76 for the normally closedcontact bar 30 is fastened to the cylindrical tube 60. These variousterminals 70, 72, 74, 76 may be supported by means of metallic discs 80which have openings for passing the terminals therethrough. The discs 80are preferably made from a magnetic material toprovide a better path forthe magnetic flux between the coil 62 and the core elements 12, 14. Thevarious terminals may be electrically insulated from the discs 80 bymeans of insulation bushings 81 formed from a thermally setting plasticwhich can be cast in the openings in the discs 80'. The completeassembly is wrapped with an electrically insulating tape 82, then placedin a metallic outer cylinder 84, and separated therefrom and supportedby a material 86 such as a thermally setting plastic which can be castand which, when cool, becomes hard. The outer cylinder 84 is preferablymade of a magnetic material to provide a better path for the magneticflux between the coil 62 and the core elements 12, 14.

When the relay is in its normal or released position, the relay elementshave the position shown in FIGURE 1. An electrically closed circuit isprovided from. the switching terminal 72 through the back portion 16,the first core element 12, the spring 22, the spring contact 26, thecontact bar 30, the support 48, the inner tube 40, the cylindrical tube60, and finally to the terminal 76 for the normally closed contact bar30. An electrically open circuit exists between the switching terminal72 and the terminal 74 for the normally open contact 34, since thesecond core element 14 and its back portion 18 are electricallyinsulated from the remainder of the relay elements. When the coil 62 isenergized, however, such as by the application of a suitable potentialto the coil terminals 70, the armature 20 is drawn up in the gap 19towards the core elements 12, 14 until the free end 28 of the spring 22engages the contact 34. The armature 20 continues to be drawn up intothe gap 19 until the faces of the armature 20 contact the correspondingend surfaces of the core elements 12, 14. This over-travel of thearmature 20 provides a desirable wiping of the free end 28 of the spring22 across the contact 34. An electrically closed circuit is thusprovided between the switching terminal 72 and the terminal 74 throughthe back portion 16, the first core element 12, the spring 22, the freeend 28, the contact 34, the second core element 14, the back portion 18,and the terminal 74. An electrically open circuit then exists betweenthe switching terminal 72 and the terminal 76 in this condition becausethe spring contact 26 is disengaged from the contact bar 30. With thearmature 20 contacting the core elements 12, 14, a good magnetic path isprovided between the core elements 12, 14, and the energizing coil 62.This path includes the outer cylinder 84, the right-hand disc 80, theback portion 16, the first core element 12, the armature 20, the secondcore element 14, the back portion 18, the left-hand disc 80, and theouter cylinder 84. However, a gap of non-magnetic material remainsbetween the outer cylinder 84- and the discs so that the relay will dropout readily when the coil 62 is de-energized.

The relay described has been successfully built and operated in anembodiment having very small physical dimensions. This embodiment had anover-all length of approximately 0.89 inch and a diameter ofapproximately 0.26 inch. Electrically, this relay was capable ofswitching a current of approximately 1 ampere at 28 volts through atleast several hundred thousands of cycles of switching. It will beappreciated that the invention provides a relay which has small physicaldimensions but which is durable and rugged. Furthermore, maximumutilization of the magnetic field is attained by the general arrangementand by the armature being near the center of the coil.

The assembly of a relay having the small physical dimensions justdescribed might, under mass-production conditions, normally be expectedto be diflicult. However, a relay. in accordance with the invention isrelatively easy to construct and assemble. The ease of construction andassembly results, at least partially, from the novel core blank 10 shownin FIGURE 3. This ease also results from the method by which the coreelements 12, 14 and the armature 20 are formed, and by which the spring22 is aligned with and fastened to the first core element 12. Acylindrical core blank 10 having the configuration shown is ground ormachined along parallel planes to provide the flat surfaces 24, 25. Ifthe flat surfaces are formed in one operation, accurate alignment of allthe elements to be fastened to the blank 10 is thus assured. After theflat surfaces 24, 25 are formed, two slots or kerfs 21 are formed in thefiat surface 25 on each side of the material in the blank 10 that willform the armature 20. The angle between the slots 21 may vary over awide range, namely from zero (in which case the slots are parallel toeach other) to an angle approaching 180 degrees. However, it ispreferred that the slots 21 converge at an angle of degrees, whichrepresents a good compromise for the various design factors involved.The contact 34 is then fastened to the flat surface of the second coreelement 14. The spring 22, which has already been provided with itscontact 26 and a welding button 27 (if needed), is fastened to the flatsurface between the grooves 21. Then, the spring 22 is provided with asuitable mechanically biasing bend near the end which will be attachedto the fiat surface 24 of the first core element 12. And then, the endof the spring 22 is suitably fastened to the first core element 12 atthe surface 24. After these operations are complete, the beads 50 arefastened to the back portions 16, 18. The inner tube 40, to which thecontact bar 30 has been previously fastened, is then passed over theblank 18 and positioned so that the contact bar 30 is adjacent andparallel to the contact 26. This positioning is easily attained. Theinner tube 40 is then fastened to the beads 50 by suitable means. Then,the blank 10 and the inner tube 40 are supported in a suitable jig orfixture, and the blank 10 is ground or machined along the dotted linesshown in FIGURE 3 so that the material 11 enclosed by the dotted linesis removed. When this material 11 is removed, the armature 21 is freedfrom the blank 10, this operation also forming the first and second coreelements 12, 14, and the X-shaped air gap 19 bounded by the inner endsurfaces of the core elements 12, 14. The various elements are held inthe proper alignment by the inner tube 48 after the material 11 isremoved. The relay is completed by adding the other elements includingthe cylindrical tube 60, the coil 62, the end portions, the terminals,and the outer cylinder 84. In addition to holding the various elementsin alignment, the inner tube 40 permits access to the elements throughthe openings between the strips 46 so that the material 11 can be easilyremoved and so that the certain elements, such as spring 22, can beadjusted if necessary. The ease of assembly and alignment of the relayelements in accordance with the method described makes the manufactureof such relays readily adaptable to mass-production techniques.

The steps in the method described may be varied, if desired, as follows:After the slot or kerfs 21 are formed, a cement such as an epoxy cementis put in the slots 21, and the material 11 is then removed. After this,the spring 22 and the beads 50 are added. Then the inner tube 40 ispassed over the blank and the beads 50 and positioned so that thecontact bar is adjacent and parallel to the contact 26. Then, a solventis applied to dissolve the cement in the slots 21, thus freeing thearmature 20. For the cement mentioned, a suitable solvent would bedichloromethane.

FIGURE 5 shows a longitudinal cross-sectional view of another embodimentof an electromagnetic relay in accordance with the invention, theembodiment of FIGURE 5 being similar to the embodiment previouslydescribed. In FIGURE 5, elements substantially identical to those inFIGURE 1 have the same reference numerals, and corresponding elementswhich may be somewhat different in form have the same reference numeralswith a prime suflixed thereto. FIGURE 5 does not show the completeelectromagnetic relay, but shows only that portion which would beassembled within the coil form 64 and coil 62. The embodiment of FIGURE5 includes first and second core elements 12', 14 having respective backportions 16', 18. Beads 50 surround the back portions 16', 18 andsupport the inner tube 40. The nonmagnetic cylindrical tube 69 surroundsthe inner tube 40 and the relay elements. A fiat spring 22 is fastenedto the first core element 12 at the surface point 24' by any suitablemeans such as welding. In the embodiment of FIGURE 5, the spring 22serves as the armature of the relay, and hence is made of a magneticmaterial which is also resilient. An example of such material is springsteel. The spring 22' carries two contacts 26', 29 which are fastened toopposite faces of the spring 22' at a point between the first and secondcore elements 12, 14. The spring 22' is bent or mechanically biased sothat its contact 26 normally engages the contact bar 30 which isfastened to the semi-cylindrical support 48. A contact 34 is supportedin the air gap 19' by a contact support 35 which is fastened tothesecond core element 14'. The spring 22, its contacts 26, 29, thecontact bar 30', and the contact 34' are allpositioned and arranged sothat the spring contact 26' normally engages the contact bar 30 when therelay is tie-energized, and so that the spring contact 29 engages thecontact 34' when the relay is energized or pulled up from its normalposition. And, it is preferable that the parts be arranged so that thereis a wiping action between the contacts, and so that the spring 22'makes contact with the second core element 14'. Since the spring 22comprises a magnetic material, a good flux path is provided between thefirst and second core elements 12', 14 when the relay is energized.

The method of assembling the embodiment shown in FIGURE 5 is similar tothe method described in connection with the embodiment shown inFIGURE 1. A blank of magnetic material having the configuration shown inFIGURE 5 is ground or machined along parallel planes to provide the flatsurfaces needed for attaching the spring 22 and the contact support 35.The beads 50 are fastened to the back portions 16', 18. The inner tube40, to which the contact bar 30' has been previously fastened, is thenpassed over the blank, and fastened to the beads 50 in such a positionthat the contact bar 30' is adjacent and parallel to the surface 24' towhich the spring 22 will be fastened. Material is then removed frombetween the portions of the blank which will form the core elements 12,14' so as to form the air gap 19'. The openings between the strips 46 ofthe inner tube readily permit this operation. After the air gap 19' isformed, the spring 22' with its contacts 26', 29 is fastened to thefirst core element 12' at the surface point 24. And finally, the contactsupport 35 with its contact 34' is fastened to the second core element14'. Then the relay may be completed as described in connection withFIGURE 1.

FIGURE 6 shows the embodiment of FIGURE 1 used in connection with apolarized relay. In FIGURE 6, elements which correspond to those inFIGURE 1, but which may be somewhat different in form, have the samereference numerals with a double prime sutfixed thereto. The relay shownin FIGURE 6 is essentially comprised of two of the working relay unitsshown in FIGURE 1, namely two first core elements 12", two second coreelements 14", and two armatures 20". These elements are positioned alongparallel lines with the same elements correspondingly located. They areheld in position by electrically insulating members positioned at theirrespective ends, the members 90 having openings to receive and firmlyhold the core elements 12", 14". A spring 22 is fastened at one end atcorresponding points on first core elements 12". The free end of thespring 22" is positioned in the vicinity of the contacts 34" which inturn are fastened at corresponding points on the second core elements14". The spring 22" is also fastened to the two armatures 20" at a pointintermediate its two ends. In operation, the spring 22" moves up or downto engage either of the two contacts 34" and provide an electricalconnection from the switching terminal to either terminal No. 1 orterminal No. 2.

If the relay shown in FIGURE 6 is to operate as a polarized relay, fourpermanent magnets 91-94 are provided at each of the respective ends ofthe core elements 12, 14". These permanent magnets 91-94 are formed ofsemi-circular flat plates, each of which has a semicircular openingtherein that is adapted to be attached to the ends of the core elements12", 14". The four permanent magnets 9194 are arranged with theirpolarities as shown, and so that the two magnets at each end form asubstantially circular frame to support a housing for the relay. If therelay coil 62" is de-energized, the magnetic flux between the lower setof magnets 91, 92 is substantially equal to the magnetic flux betweenthe upper set of magnets '93, 94. However, the spring 22 will movetoward and engage one of the contacts 34", and remain in this position.In FIGURE 6, it is assumed that the spring 22" moved downward. If therelay coil 62 is energized with one direction of current so that themagnetic flux provided by the coil 62 opposes the magnetic flux betweenthe lower set of magnets 91, 92 by substantially the same amount offlux, and aids the magnetic flux between the upper set of magnets 93,94, then there is very little, if any, magnetic flux in the lowerarmature 20" and a relatively large magnetic flux in the upper armature20". Consequently, the spring 22" moves upward. This provides anelectrical connection from the switching terminal to terminal No. 1.However, if the direction of current flow through the relay coil 2" isreversed with respect to the original current direction, then the spring22 will move downward to provide an electrical connection between theswitching terminal and terminal No. 2. Thus, polarized operation of arelay in accordance with the invention is provided.

The method by which the relay shown in FIGURE 6 can be manufactured issubstantially similar to the method explained in connection with'theassembly of the relays shown in FIGURES 1 through 5. The core elements12", 14",.the armatures 20", and the spring 22" are assembled and heldin position by the inner tube 40". The inner tube 40 does not have thesemi=cylindrical support 48 shown and described in connection with therelays of FIGURES 1 through 5, as the contacts 34" for the spring 22"are carried by the second core elements 14". With the relay units housedand fastened within the inner tube 40", the armatures 20" are freed bymachining or grinding, thus providing and insuring the alignmentdesired. One slight difference might be mentioned in connection with theembodiment of FIG- URE 6, namely the shape ofthe air gaps. In theembodiment shown in FIGURE 6, after the slots have been cut into therespective blanks, and the blanks fastened in the inner tube 40", thearmatures 20" are freed by removing material in such a manner that theslots are, in effect, continued through the blanks to provide the airgap shape shown. However, this feature is one of design and choice, andmay be varied to a great extent without departing from the spirit of theinvention.

From the above description, it will be seen that a relay in accordancewith the invention may have relatively small physical dimensions and maybe manufactured with mass-production methods.

While the invention has been described with reference to particularembodiments, it is to be understood that modifications may be made bypersons skilled in the art without departing from the spirit of theinvention or from the scope of the claims.

What I claim as new and desire to secure by Letters Patent of the UnitedStates is:

1. A magnetic switch comprising a core having first and secondelementsof magnetic material, said elements being separated by a gap, anelongated spring having one end fastened to said first element and theother end positioned in the vicinityof but normally separated from saidsecond element, said spring comprising an armature of magnetic materialpositioned in the vicinity of said gap and normally spaced from saidelements, a metallic tube positioned at least partially around saidelements and said spring comprising said armature, and a contactfastened to said tube and positioned adjacent said spring, said springbeing biased so that said spring normally engages said contact.

2. An electromagnetic relay comprising a core having first and secondelements of magnetic material, said elements being separated by an airgap, a fiat elongated spring having one end fastened to said firstelement and the other end positioned in the vicinity of but normallyseparated from said second element, an armature of magnetic materialfastened to said spring, said armature being positioned in the vicinityof said gap and normally spaced from said elements, a metallic elementsurrounding at least a portion of said first and second elements, saidspring, and said armature, a contact fastened to said metallic elementand positioned adjacent said spring in the vicinity of said gap, saidspring being biased so that said spring normally engages said contact,and an energizing coil positioned around at least a portion of saidmetallic element.

3. An electromagnetic relay comprising a core having first and secondelements of magnetic material, said elements being separated by a gap, aflat elongated spring having one end fastened to said first element andthe other end free and positioned in the vicinity of but normallyseparated from said second element, an armature fastened to said springintermediate the ends thereof, a first contact positioned adjacent saidspring in the vicinity of said gap, said spring being biased so thatsaid other end of said spring normally contacts said first contact, anda second contact supported by said second element and positioned in thevicinity of said gap, said spring being normally'spaced from said secondcontact.

4. An electromagnetic relay comprising a core having first and secondelements of magnetic material, said elements being separated'by a gap,anelongated spring .hav-

ing one end fastened to said first element and the other end positionedin the vicinity of but normally separated from said second element, anarmature of magnetic material fastened to said spring, at least aportion of said armature being positioned in said gap and spaced fromsaid elements, a metallic tube having at least one opening thereinpositioned around said first and second elements, said spring, and saidarmature, a contact bar fastened to and positioned within said tube andadjacent said spring, said spring being biased so that said springnormally contacts said contact bar, and an energizing coil positionedaround said tube whereby said relay provides a closed circuit betweensaid first element and said tube and an open circuit between said firstelement and said second element in response to said coil beingde-energized and whereby, in response to said coil being energized, saidspring is drawn toward said second element to provide a closed circuitbetween said first element and said second element and an open circuitbetween said first element and said tube.

5. An electromagnetic relay comprising a core having first and secondelements of magnetic material, said elements being separated by a gap,an elongated spring formed of magnetic material and having one endfastened to said first element and the other end free and positioned inthe vicinity of but normally separated from said second element, a firstcontact positioned adjacent said spring in the vicinity of said gap,said spring being biased so that said spring normally contacts saidfirst contact, a second contact supported by said second element in thevicinity of said gap and positioned so that said spring is normallyseparated from said second contact, a metallic inner tube having accessopenings positioned around said elements and said spring, said tubebeing fastened to said first contact, and an energizing coil positionedaround said inner tube whereby said relay provides a closed circuitbetween said first element and said inner tube and an open circuitbetween said first element and said second contact in response to saidcoil being de-energized and whereby said spring, in response to saidcoil being energized, is drawn toward said second element to provide aclosed circuit between said first element and said second contact and anopen circuit between said first element and said inner tube.

6. An electromagnetic relay comprising a core having first and secondelements of magnetic material positioned along a common straight line,said elements being separated by a gap formed by adjacent end surfacesof said elements, a flat elongated metallic spring having one endfastened to said first element and the other end positioned in thevicinity of but normally separated from said second element, an armatureof magnetic material, means fastening said armature to said spring withsaid armature being positioned in a registered relation to a portion ofsaid gap but spaced from said end surfaces of said elements, anelongated metallic inner tube having access openings, said inner tubebeing positioned along said straight line and generally surrounding saidelements, said spring, and said armature, a metallic contact barfastened to said inner tube and positioned adjacent said spring inthevicinity of said gap, said spring being biased so that said springnormally contacts said contact bar, and an energizing coil positionedalong said straight line around said inner tube whereby said relayprovides a closed circuit between said first element and said inner tubeand an open circuit between said first element and said second elementin response to said coil being deenergized and whereby said spring, inresponse to said coil being energized, is drawn toward said secondelement to provide a closed circuit between said first element and saidsecond element and an open circuit between said first element and saidinner tube.

7. An electromagnetic relay comprising a core having first and secondsubstantially cylindrical elements of magnetic material positioned sothat their longitudinal axes lie along a common straight line, saidelements being separated by a gap formed by adjacent end surfaces ofsaid elements, said end surfaces lying in converging planes, anelongated metallic spring having one end fastened to said first elementand the other end free and positioned in the vicinity of but normallyseparated from said second element, an armature of magnetic materialhaving substantially the same size as said gap, means fastening saidarmature to the side of said spring facing said elements with saidarmature being positioned intermediate the ends of said spring in aregistered relation to a portion of said gap but spaced from said endsurfaces of said elements, a metallic contact bar positioned adjacentsaid spring in the vicinity of said gap, said spring being biased sothat the side of said spring away from said elements normally engagessaid contact bar, and an energizing coil positioned along said straightline around said elements, said spring, said armature, and said contactbar whereby said relay provides a closed circuit between said firstelement and said contact bar and an open circuit between said firstelement and said second element in response to said coil beingde-energized and whereby said spring, in response to said coil beingenergized, is drawn toward said second element to provide a closedcircuit between said first element and said second element and an opencircuit between said first element and said contact bar.

8. An electromagnetic relay comprising a core having first and secondsubstantially cylindrical elements of magnetic material positioned sothat their longitudinal axes lie along a common straight line, saidelements being separated by a gap formed by adjacent end surfaces ofsaid elements, an elongated metallic spring having one end fastened tosaid first element and the other end positioned in the vicinity of butnormally separated from said second element, at least a portion of saidspring being comprised of a magnetic material, means fastening a firstcontact to said spring in the vicinity of said gap so that said firstcontact faces said gap, means fastening a second contact to said springin the vicinity of said gap so that said second contact faces away fromsaid gap, a metallic contact bar positioned adjacent said spring in thevicinity of said gap, said spring being biased so that said secondcontact normally engages said contact bar, a third contact positioned insaid gap and supported by said second element so that said first contactis normally separated from said third contact, and an energizing coilpositioned along said straight line around said elements, said spring,said contacts and said contact bar whereby said relay provides a closedcircuit between said first element and said contact bar and an opencircuit between said first element and said second element in responseto said coil being de-energized and whereby said spring, in response tosaid coil being energized, is drawn toward said second element toprovide a closed circuit between said first element and said secondelement and an open circuit between said first element and said contactbar.

9. An electromagnetic relay comprising a core having first and secondsubstantially cylindrical elements of magnetic material positioned sothat their longitudinal axes lie along a common straight line, saidelements being separated by a gap formed by adjacent end surfaces ofsaid elements, a fiat elongated metallic spring having one flat side atone end thereof fastened to said first element so that said one flatside faces said gap and having the other end thereof positioned in thevicinity of but normally separated from said second element, an armatureof magnetic material having substantially the same shape and size as atleast a portion of said gap, means fastening said armature to said oneflat side of said spring with said armature being positionedintermediate the ends of said spring in a registered relation to aportion of said gap but spaced from said end surfaces of said elements,an elongated metallic inner tube having access openings, said inner tubebeing positioned along said straight line around at least a portion ofsaid elements, said spring, and said armature, a flat metallic contactbar fastened to and positioned within said inner tube and adjacent thefiat side of said spring away from said elements in the vicinity of saidgap, said spring being biased so that said spring normally contacts saidcontact bar, and an energizing coil positioned along said straight linearound said inner tube whereby said relay provides a closed circuitbetween said first element and said inner tube and an open circuitbetween said first element and said second element in response to saidcoil being de-energized and whereby said spring, in response to saidcoil being energized, is drawn toward said second element to provide aclosed circuit between said first element and said second element and anopen circuit between said first element and said inner tube.

10. An electromagnetic relay comprising a core having first and secondsubstantially cylindrical elements of magnetic material positioned sothat their longitudinal axes lie along a common straight line, saidelements being separated by a substantially X-shaped gap formed by theinner end surfaces of said elements, an insulator fastened to each ofsaid elements in the vicinity of the respective outer ends thereof, afiat elongated metallic spring having one flat side at one end thereoffastened to said first element so that said one fiat side faces said gapand having the other end thereof positioned in the vicinity of butnormally separated from said second element, an armature of magneticmaterial having substantially the same shape and size as at least aportion of said gap, means fastening said armature to said one fiat sideof said spring with said armature being positioned in a registeredrelation to a portion of said gap but normally spaced from said innerend surfaces of said elements, an elongated metallic contact barsupported between said insulators and adjacent the flat side of saidspring away from said elements in the vicinity of said gap, said springbeing biased so that said spring normally contacts said contact bar, ahollow metallic cylinder symmetrically positioned with respect to saidstraight line and surrounding said elements, said spring, said armature,and said contact bar, and an energizing coil surrounding said hollowcylinder whereby said relay provides a closed circuit between said firstelement and said contact bar and an open circuit between said firstelement and said second element in response to said coil beingde-energized and whereby said spring, in response to said coil beingenergized, is drawn toward said second element to provide a closedcircuit between said first element and said second element and an opencircuit between said first element and said contact bar.

11. An electromagnetic relay comprising a core having first and secondsubstantially cylindrical elements of mag netic material positioned sothat their longitudinal axes lie along a common straight line, saidelements being separated by a substantially X-shaped gap formed by theinner end surfaces of said elements, said inner end surfaces lying inconverging planes, an insulating bead fastened around each of saidelements in the vicinity of the respective outer ends thereof, a flatelongated metallic spring having one fiat side at one end thereoffastened to said first element so that said one fiat side faces said gapand having the other end thereof positioned in the vicinity of saidsecond element, said spring being mechanically biased so that said otherend thereof is normally separated from said second element, an armatureof magnetic material having substantially the same shape and size as atleast a portion of said gap, means fastening said armature to said oneflat side of said spring with said armature being positioned in aregistered relation to a portion a said gap but spaced from said innerend surfaces of said elements, an elongated metallic contact barsupported between said insulators and positioned adjacent the fiat sideof said spring away from said elements in the vicinity of said gap, saidspring being 11 biased so that said spring normally contacts saidcontact bar, a hollow metallic cylinder symmetrically positioned withrespect to said straight line and surrounding said elements, saidspring, said armature, said contact bar, and said insulating beads, andan energizing coil surrounding said hollow cylinder whereby said relayprovides a closed circuit between said first element and said contactbar and an open circuit between said first element and said secondelement in response to said coil being de-energized and whereby saidspring, in response to said coil being energized, is drawn toward saidsecond element to provide a closed circuit between said first 12 elementand said second element and an open circuit between said first elementand said contact bar.

References-Cited in the file of this patent UNITED STATES PATENTS2,394,724 Snorek Feb. 12, 1946 2,481,003 Curtis Sept. 6, 1949 2,483,723Burton Oct. 4, 1949 2,767,279 Hall Oct. 16, 1956 2,834,848 Ellwood May13, 1958 2,840,660 Ducati June 24, 1958 2,848,661 Amouriq Aug. 19, 19582,860,403 Meyer Nov. 18, 1958 UNITED STATES PATENT OFFICE CERTIFICATE OFCORRECTION Patent No, 2,993 104 July 18, 1961 John S Zimmer It is herebycertified that error appears in the above numbered patent requiringcorrection and that the said Letters Patent should read as correctedbelow.

Column 10, line 71 for "a" Signed and sealed this 19th day of December1961.

(SEAL) Attest:

ERNEST W. SWIDER Attesting Officer DAVID L. LADD Commissioner of PatentsUSCO M M -DC UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTIONPatent N0 2,993,104 July l8 1961 John 5. Zimmer It is hereby certifiedthat error appears in the above numbered patent requiring correction andthat the said Letters Patent should read as corrected below. 7

Column l0 line 71 for "13" second occurrence read of Signed and sealedthis 19th day of December 1961.

(SEAL) Attest:

ERNEST W. SWIDER I DAVID L. LADD Attesting Officer Commissioner ofPatents USCOMM-DC

